1. Field of the Invention
The present invention relates to a high speed transmission connector.
2. Description of the Related Art
A high speed transmission connector, including a plurality of signal contact pairs which are arranged in a parallel array and each of which includes a pair of signal contacts constituting a balanced transmission line, a plurality of ground contacts which are arranged alternately relative to the signal contact pairs and each of which is arranged between two of signal contact pairs arranged in the parallel array, and an electro-insulating body which supports the signal contact pairs and the ground contacts in a mutually insulated arrangement, is conventionally known (see, e.g., Japanese Patent No. 3685908). In this configuration, a signal contact pair constituting a balanced transmission line which is unlikely to be affected by noise is used, and in addition, cross talk between adjacent signal contact pairs is suppressed by arranging a ground contact between the two signal contact pairs arranged side-by-side, so that signal transmission characteristics of the connector can be significantly improved.
In a case where the above high speed transmission connector is configured for circuit-board mount use, each signal contact is provided with a contacting section at one longitudinal end for coming into conductive contact with a corresponding signal contact of a counterpart connector, and a board connecting section at the other longitudinal end for connection to a conductor on the circuit board. In view of reducing the difference in signal transmission time in a balanced transmission (also called differential transmission) as much as possible, it is advantageous that a pair of signal contacts constituting each signal contact pair have shapes and dimensions identical to each other.
In a conventional high speed transmission connector for a circuit board as described above, in the case where the pair of signal contacts constituting each signal contact pair have mutually identical shapes and dimensions, the board connecting sections of individual signal contacts are disposed respectively along a pair of lateral surfaces of a connector body, extending in a longitudinal direction (in the direction of a contact array). Thus, when the high speed transmission connector is to be connected, on the circuit board, to another electronic component disposed, for example, in close proximity to one of the lateral surfaces of the body, a conductor pattern connecting the two may become complicated depending on the relative position between the connector and the electronic part. In particular, since it is required also for conductors formed by patterning on the circuit board that difference in the signal transmission time in balanced transmission be reduced as much as possible, it is desirable that a pair of conductors connected to a signal contact pair have the same length. As a result, this may further complicate the conductor pattern.
On the other hand, another configuration is known in which, by forming the neighborhood region of respective board connecting sections of a pair of signal contacts constituting the signal contact pairs in shapes different from each other, board connecting sections of all the signal contact pairs are disposed along only one lateral surface of the connector body. With this configuration, when the high speed transmission connector is to be connected to another electronic part disposed in close proximity to one lateral surface of the connector body on the circuit board, the conductor pattern connecting the two can be simplified.
However, with this configuration, in each signal contact pair, one of the signal contacts has shorter spatial distance between the contacting section and the board connecting section than that of the other signal contact, and this may leads to a problem of difference in signal transmission time in balanced transmission. In order to avoid this problem, in a generally adopted approach, the neighborhood region of the board connecting section of the signal contact having the smaller distance between the contacting section and the board connecting section is formed in a curved shape locally bent toward the other signal contact such that there is no difference in total length between the two contacts. However, this may lead to another problem that, in such a contact having curved portion with small radius of curvature, the signal transmission characteristics may deteriorate due to a magnetic field disturbance that may arise from the curved portion.